The ::value_type of the std::map/std::multimap/std::unordered_map containers is std::pair<const Key, T>. Dropping the const results in an unnecessary copy, for example in C++11 range-based loops. For this I started with a more general scripted diff, then narrowed it down based on the inspection showing that all actual map/multimap/unordered_map variables used in loops start with m or have map in the name. -BEGIN VERIFY SCRIPT- sed -i -E 's/for \(([^<]*)std::pair<([^c])(.+) : m/for (\1std::pair<const \2\3 : m/' src/*.cpp src/**/*.cpp sed -i -E 's/for \(([^<]*)std::pair<([^c])(.+) : (.*)map/for (\1std::pair<const \2\3 : \4map/' src/*.cpp src/**/*.cpp -END VERIFY SCRIPT-
Backport of core PR13241
Note to reviewers:
There is a couple of changes not backported from the PR, due to missing
dependencies regarding the wallet label API. A follow-up diff will
backport PR13480 and introduce a clang warning to detect copies in
loops, so I think this is safe to leave it for now.